Referring to FIG. 1, a conventional record player for playing an acoustical record 10 includes a spindle 11, a platter 12, a tonearm assembly 13, a shading disk 14 and a conventional monitoring unit 15. The platter 12 is co-rotatably connected to the spindle 11, and allows the acoustical record 10 to be placed thereon. The tonearm assembly 13 is used to read the acoustical record 10 for producing sound stored by the acoustical record 10. The shading disk 14 is co-rotatably connected to a bottom end of the spindle 11, has a surface provided with multiple marks arranged radially and spaced angularly from each other, and can coaxially co-rotate with the platter 12 as well as the acoustical record 10 placed on the platter 12. The conventional monitoring unit 15 is configured to detect a rotating speed and a rotating direction of the shading disk 14.
Since the shading disk 14 co-rotates with the platter 12 and the acoustical record 10, the rotating speed and the rotating direction of the shading disk 14 detected by the conventional monitoring unit 15 are substantially identical to a rotating speed and a rotating direction of the acoustical record 10. In detail, light reflected by the shading disk 14 may vary due to the marks thereon. Accordingly, the conventional monitoring unit 15 is configured to detect variation of brightness of the light reflected by the shading disk 14, so as to determine the rotating speed of the shading disk 14, and in turn the rotating speed of the acoustical record 10. However, it is necessary to provide an additional inner space in the conventional record player to accommodate the shading disk 14.